1994 90HP Force Problems

[Koffi]

My motor runs fine until you stop it for about 15 minutes, then, when you crank it and try to go, it will die as you go through midrange. The only way to get it past midrange is to quickly go to full throttle and then, most of the time, it will go. I have replaced the fuel pump and even had it rebuilt. I have replaced the hoses from the fuel tank to the fuel pump. I have replaced the fuel filter. I have had the carbs rebuilt twice. The bulb has been changed numerous times (all work was done by a Mercury dealer). <br /><br />Any ideas? This has been a 4 year problem that has cost me about $2000! I know, that's more than the motor is worth, but every fix was supposed to be the one that worked. The serial number of the motor is 0EO32740

 

[roscoe]

Re: 1994 90HP Force Problems

Welcome to iboats.<br /><br />Hmmmm, What if you let it sit for 2-3 hours?<br />Is all ok then?<br /><br />This may take a while, but someone will figure it out. And its free !!

 

[roscoe]

Re: 1994 90HP Force Problems

Almost sounds like a couple of things. <br />But the fact that it runs fine till you turn it off doesn't fit.<br /><br />You aren't running in the mountains are you?

 

[eurolarva]

Re: 1994 90HP Force Problems

Is the gas tank portable or built into the boat? Do you have a quick disconnect for the gas? When you restart motor is the fuel bulb firm or soft?

 

[Koffi]

Re: 1994 90HP Force Problems

The gas tank is built in the boat and I did away with the quick disconnect thinking that that might be the problem. The bulb continues to be firm even after the problem. The boat runs fine the first time in the water...it goes through midrange exactly as it should. However, when I stop it and let it sit for around 15 minutes (give or take a few minutes), it dies if I try to go SLOWLY through midrange. However, if I nail it and it doesn't die, I can slow it down and THEN it will go through midrange as it should. It sounds as if it's losing prime somewhere, but nobody can figure out where.

 

[eurolarva]

Re: 1994 90HP Force Problems

Sounds to me like the motor is flooding when it is stopped. When you run it at full speed and burn out the excess fuel your problem goes away. My guess would be a bad fuel pump. If the motor had a quick disconnect I was going to recommend disconnecting it while motor was running and then kill the motor and see if the condition repeats. Does this motor have a standard choke or one of the fuel enrichment sytems on it?

 

[roscoe]

Re: 1994 90HP Force Problems

Yes, but the motors I have experience flooding at stop, were so flooded that they would not start, or idle. Seems odd that it only pops up when warm, stopped, and then at midrange rpm.<br /><br />Does it cough or sneeze or sputter when it is about to die, or just stop?

 

[Koffi]

Re: 1994 90HP Force Problems

Actually, it doesn't even have to be warm. Crank it up, kill it, let it sit for approx. 15 minutes, and it has no midrange. I don't think it's flooding since, after it dies, it will crank as soon as you hit the starter. When I advance the throttle SLOWLY, it sounds as if it's starving for fuel (although it doesn't help to hit the choke). I tried decarbing it today, but still no luck. I appreciate all the help. Keep the ideas coming and I will continue to try them.

 

[roscoe]

Re: 1994 90HP Force Problems

Hmmmm,<br />Almost like the linkage that advances the timing isn't moving. But that makes no sense if it will operate properly at other times.<br /><br />Ralph, I have to ask if you have a repair manual, and if so, which one? Can refer you to a few diagrams if you have a manual.<br /><br />Gonna go out on a limb here and suggest you check the fuel recirculation system. Check the hoses for blockage or leaks, and clean the check valves.<br /><br />Thinking that is where the semi flooded condition may be coming from. Maybe one stuck check valve. Or the valve or hose is cracked and sucking air?<br /><br />Read somewhere that the recirc system not only effects idle, but midrange and accelleration also.<br /><br />SHot in the dark I know, but I'm about out of ideas.<br /><br />What do you think euro?

 

[eurolarva]

Re: 1994 90HP Force Problems

My answer is a shot in the dark about the flooding however I think the recirculation system would be a good place to look. Newer chryslers have a screen that gets plugged and cause similar to flooded condition. Mainly affects idle. This was also refered to as puddle valves.

 

[Koffi]

Re: 1994 90HP Force Problems

Yes, I do have a manual, but no I don't know what kind it is (it's out in my shop and it's snowing in North AL). I took the lines loose from the 3 check valves on the front of the motor, behind the carbs. I checked them by blowing and sucking on the tubing and all were working. I also changed the tubing while I was at it. Still no luck. My manual says that the recirculation system can affect acceleration. Would it be wise to go ahead and change the check valves just in case? I appreciate your help.

 

[Koffi]

Re: 1994 90HP Force Problems

I forgot to add that I did get the manual from Mercury.

 

[roscoe]

Re: 1994 90HP Force Problems

The '94 has the square fuel pump, correct?<br /><br />Your motor should look like this:<br /><br />

<br /><br />You have three check valves on the port side (number 2 in the picture) $7 each. And three "T" check valves on the starboard side (the 3 closest to the carbs) (number 5 in the picture). $14 each.<br /><br />And 3 elbow fittings on the rear of the starboard side, they are just fittings, no check valves. (number 1 in the picture)<br /><br />So you have 6 check valves to check.<br /><br />Sometimes you can clean them if they are stuck.<br /><br />If a checkvalve is stuck open, it will allow fuel to flow thru, into the engine.

 

[Koffi]

Re: 1994 90HP Force Problems

Roscoe,<br /><br />I did verify that the check valves #2 were working. I also ordered the "T" check valves from my Mercury deal just in case they were bad, but when I removed the bracket that holds the electronics so I could get to the check valves and hoses, mine did not have the "T" check valves. The hoses ran from the check valves that are just behind the carbs to the elbows on the starboard side of the motor. Have you ever seen a Force without the "T" check valves?

 

[roscoe]

Re: 1994 90HP Force Problems

The 91 and 92c model motors have the round fuel pump, and only had check valves on the port side, and they looked like this:<br /><br />

<br /> <br /><br /><br />Some later models are also be set up this way. Specifically, those with serial numbers E009500 thru E065371. <br /><br /><br />

<br /><br /><br />Those with serial numbers E065372 thru E093699, are set up with the "T" check valves like in the diagram in the previous post. Which should include most of the 1994 models, as they should have the higher serial numbers.

 

[roscoe]

Re: 1994 90HP Force Problems

Presuming you have the older design:<br /><br />Parts 12,13,14 above, are known as the cylinder drain.<br /><br />Remove then and inspect. There are screens in them that need to be cleaned out periodically. If they are plugged, you have problems.

 

[Koffi]

Re: 1994 90HP Force Problems

I haven't checked that. Could you give me some specifics on how to go about it or would I be better off letting the dealer do the work?

 

[Koffi]

Re: 1994 90HP Force Problems

I forgot to mention that I do have the older type (serial #0E032740).

 

[roscoe]

Re: 1994 90HP Force Problems

You just have to unbolt that cover and remove. Then clean out the screens.<br />Careful not to damage the gasket, or you will have to replace.<br /><br />Also, parts 8,9,10, and 11 are small pieces, don't drop them, or lose them.

 

[Koffi]

Re: 1994 90HP Force Problems

Do the reeds present any problems? And, should I replace them while I have it down?